Saturday, 1 March 2014

Generalization in data base management | Database management


It is the form of abstraction that specifies that 2 or more entities that share common attributes can be generalized into a higher level entity time called a super type or a generic entity. The lower levels of entities become the sub type to the super type.It is used to emphasis the similarities among the lower level entity sets and to hide the differences.It makes the ER diagram simpler because shared attributes are not repeated. 
           A generalization is an extension of the concept to less-specific criteria. It is a foundation element of logic and human reasoning.
         Generalizations posit the existence of a domain or set of elements, as well as one or more common characteristics shared by those elements. As such, they are the essential basis of all valid deductive inferences. The process of verification is necessary to determine whether a generalization holds true for any given situation.

EXAMPLE:-There are 2 department(ENGG,MGMT) which is generalized into DEPT and the attributes which are common between these two are placed together.



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